CurtPalme.com Home Theater Forum

conan7123 · Joined: 28 Jun 2014 Posts: 8 Location: Germany

Hello, I have a big problem with my Zenith Pro 861 projector.
It was 8 or 9 years in the basement and my brother wanted to throw it away, so I grabbed it and was testing around with it.
The first 30 minutes the projector was working fine (okay, I only saw the menu because I didn´t had an bnc to rca adapter), but after I unplugged it from the wall and later wanted to use it, it won´t turn on.

After I removed the backcover the fuse (250V, 2A) was blown out, a new one didn´t last long (blown out directly).
After some testing I figured out that the left power board ( your Zenith 841 page says HV and convergence power supply)
kills the fuse.
After I removed it , it turns on again (I hear the tubes and the speakers), so the left power supply must be shorted out..

Now the question is: Is there any way to repair the board or to get a replacement?
Or is the chance to high that the board has destroyed the other boards?

Any suggestion would be great

some pictures:

http://ts3.kev-ps-server.de/zenith/kpplpro861/IMG_6881.JPG

http://ts3.kev-ps-server.de/zenith/kpplpro861/IMG_6882.JPG

http://ts3.kev-ps-server.de/zenith/kpplpro861/IMG_6884.JPG

http://ts3.kev-ps-server.de/zenith/kpplpro861/IMG_6885.JPG

http://ts3.kev-ps-server.de/zenith/kpplpro861/IMG_6888.JPG

http://ts3.kev-ps-server.de/zenith/kpplpro861/IMG_6891.JPG

http://ts3.kev-ps-server.de/zenith/kpplpro861/IMG_6893.JPG

**Curt Palme** · Posted: Sun Jun 29, 2014 10:01 pm Post subject:

Where were you 3 years ago? I threw out about 10 brand new 220 volt versions of this supply!

But.. I can help you fix yours, as it's usualyl a very simple fix.

The mica insulator behind the transistor on the heat sink fails, and shorts the collector (metal tab) of the heatsink to the metal heatsink, causing a direct short.

Replace the mica insulator, and it should work again.

conan7123 · Joined: 28 Jun 2014 Posts: 8 Location: Germany

Hey Curt Palme,
you´re making me really happy right now Very Happy

I think I will search for a new transistor tomorrow, I hope that will fix the board, but I have some consider..
The projector was bought by ebay almost 10 years ago and wasn´t used (my brother didn´t know that he must use the bnc input and not the y/c vcr rca).
The first problem I saw was that the ground cable on the socket was cutted, also the fuse (normally 250V, 2A) was a 250V 4A fuse, I hope the board isn´t grilled.....

But I have one more question:
I have some "basics" about electrical engineering (two weeks ago I have finished my education of information technology assistant - computer stuff) but i have tested some resistor and one resistor might failed, because I can´t measure it, also the blue thing (condensator???) behind it, my multimeter won´t show any value.

http://ts3.kev-ps-server.de/zenith/kpplpro861/IMG_6894.JPG

What do you think about it?

**Curt Palme** · Posted: Mon Jun 30, 2014 12:59 am Post subject:

I think the transistor and the capacitor (that's what the blue thing is I think) are probably fine. See the dirt behind the transistor?

Take the clamp off that holds the transistor to the heat sink, and pull the transistor forward. I'm sure that dirt will show up as an arcing point behind the transistor. Clean that up, put on a new mica insulator, and I'm sure it will be fine.

Heck, to test it, take the clamp off, pull forward on the transistor so that it is not touching the mica or the heatsink, and power the set up.

If it works and doesn't blow the fuse, you're fine as soon as you get new mica.

Don't run it for more than long enough to see if the tubes light up.

Also, Zenith made me a lot of money over the years by people that plugged their video (or cablevision RF) signal into the RCA Y/C connector. I did a service call once just outside of town, knowing the guy had it connected incorrectly, and despite me telling him 10X on the phone what the problem was, he insisted that I come out. I said it was $250, as it was a 2 hour trip, and I was there for about 3 minutes. He paid. Smile

conan7123 · Joined: 28 Jun 2014 Posts: 8 Location: Germany

I clean the transistor (isopropyl alcohol) and test it like this?

http://ts3.kev-ps-server.de/zenith/kpplpro861/IMG_6902.JPG

*edit*
cool, after i pushed it away from the heatsink, the solder breaked... where is my soldering iron..
Now I can unsolder it and clean it really good..

**Curt Palme** · Posted: Mon Jun 30, 2014 1:39 am Post subject:

Exactly! you can measure across the 3 leads in all combinations with an ohmmeter to see if you get 0 ohms across any 2 leads. (if so, the transistor is probably shorted), but I'll bet it's OK.

conan7123 · Joined: 28 Jun 2014 Posts: 8 Location: Germany

Nope, another blown fuse Very Happy

http://ts3.kev-ps-server.de/zenith/kpplpro861/fuse *video of the new fuse :/ after i plug it in it gets killed*

I test it with an ohmmeter and between pin 1 and pin 2 it has a resistance at 20kOhm and its rising, pin 3 dosen´t make anything.

Tim in Phoenix · Joined: 21 Oct 2006 Posts: 4409 Location: Phoenix

Hello

I would not spend much time or money on this thing, it is bordering on obsolete. You can find Barco or Electrohome machines under $1500 that would run circles around it

conan7123 · Joined: 28 Jun 2014 Posts: 8 Location: Germany

Hmm.... I think I mess with it around a bit more Very Happy

I don´t know if I would buy an projector..... This "little" machine didn´t cost me anything.. I also would need a screen to project on it Very Happy

As a student you don´t have any money.. In September my apprenticeship starts (yay, money Very Happy

)

But I have looked around and found an Barco Graphics 801 for about 250€ (~341 USD) not far away from me, it says:
2000 hours
no burns
technically okay
User Manual, Remote, cables
aand I could get an Barco 800 (not working) for tube or board replacement for free
Link: (German) http://kleinanzeigen.ebay.de/anzeigen/s-anzeige/beamer-roehrenprojektor-barco-801/205846901-175-2064?ref=search

I don´t know....

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

**Curt Palme** · Posted: Mon Jun 30, 2014 12:59 pm Post subject:

OK, let me check my projector here, I know the 220 volt board is a bit different. I would check all semiconductors and diodes on the boards for a short. I'm sure you have a dead short on that board somewhere.

conan7123 · Joined: 28 Jun 2014 Posts: 8 Location: Germany

Okay, I will check for that Very Happy

thanks

But I contacted the person with the Barco 801 and I will try to go down to 150€ (~204 USD) with the broken Barco 800 (my Dad would give me the 150€)

I don´t know how to thank you all Embarassed

conan7123 · Joined: 28 Jun 2014 Posts: 8 Location: Germany

Hmmm
I dont know what this means but I removed one Diode and used a 4A fuse (because I only have 2 of the 2Amps here) and the green tube comes on, i will solder the diode in and test it

*edit*

OoOoOoOo

okay... I soldered it all together with the old parts and now I use a 4 A fuse the f*cking thing powers up..... but the Picture is flickering as hell

*edit2*
okay, another dvd stopped the flickering
now I set it on my desk and try to configure it Razz

I hope there are no mask/burns, but the tupes from the looking at seems very dirty -.-

*edit3*
but first I will flip the screen Very Happy

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

It looks like you have fungus in those tubes.

conan7123 · Joined: 28 Jun 2014 Posts: 8 Location: Germany

I can not remove the glas, right?
I think there is glycol in there.

http://ts3.kev-ps-server.de/zenith/kpplpro861/IMG_6907.JPG

**Curt Palme** · Posted: Mon Jun 30, 2014 10:10 pm Post subject:

You need to take the tubes out, remove the glass, drain the glycol and fill with new stuff. Very common on those Zeniths, and that one is really bad. Smile

Also make sure you properly clean and flush the LC chamber, especially the rubber bellows at the top, as lots of gunk gets stored in there. Pull everything apart and refill with clean glycol. I've got lots if you can't find any.